Central-office switchboard system



(No Model.) 2Sheets-Sheetl. W. S. 8: E. M. HARRISON.

CENTRAL OFFICE SWITGHBOARD SYSTEM. No. 587,502. Patented Aug. 3,1891

2 Sheets Sheet 2.

(NoModeL) W. S. & E. M. HARRISON. CENTRAL OFFICE SWITOHBOARD SYSTEM. No.587,502. Patented Aug. 3,1897.

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I UNITED STATES PATENT EErcE.

\VILLIAM S. HARRISON AND EDlVARD M. HARRISON, OF CHICAGO, ILLINOIS.

CENTRAL-OFFICE SWITCHBOARD SYSTEM.

FECIFICATION forming part of Letters Patent No. 587,502, dated August 3,1897.

Application filed March 30, 1895. Serial No. 543,869. (No model.)

To ctZZ whom it may concern.-

Be it known that we, WILLIAM S. HARRL son and EDWARD M. HARRISON,citizens of the United States, residing at Chicago, in the county ofCook and State of Illinois, have invented certain new and usefulImprovements in CBIltlELl-Ol'fiOG Switchboard Systems; and we do herebydeclare the following to be a full, clear, and exact description of theinvention, such as will enable others skilled in the art to which itappertains to make and use the same.

This invention relates to a central-office telephone-exchange systemembracing various connecting devices, such as a transferboard, as a partof a switchboard and containing ground lightning-arrester post-s,spring-jack switches, having suitable switchplugs, polarizedannunciators, switchboardreceiv'ers, and suitable details and electricalconnections for constituting a complete telephone central office, aswill be hereinafter particularly pointed out in connect-ion with theaccompanying drawings.

The objects of our invention are, first, to provide for concentratingthe live wires on a transfer-board and for quickly and convenientlymaking transfer connections from the binding-post in any one section ofsuch transfer-board to any binding-post in an adjacent section thereofwithout disturbing the connections of the wires from the transfer-boardto the switchboard; second, to provide in the transfer-board a groundlightning-arrester post for eachlin e-wire,said post being permanentlysecured to a common groundplate and insulated wires of slight resistancecoiled around said lightning arrester posts and thence connecting withthe binding-posts in adjacent sections of the transfer-board, saidground-plate being connected by wire with the earth; third, to provideacombination springjack switch having suitable connections for thepurpose of cutting the line-wire in and out of circuit with the annunciator and at the same time ringing a distant bell; third, to providepairs or couples of switch-plugs having electrical connect-ions andinsulating material suitably arranged for use with the spring-jackswitches for bringing one line into connection with another and at thesame time cutting the annunciator of one line out of circuit andbringing the annunciator of the other line into circuit with theopposite telephone-line; fifth, to provide a polarized annunciatorhaving a swinging armature connecting with a sliding push needle or rodso arranged that when a current is passed through the coil the saidarmature will be drawn to the core, thereby actuating said needle andkicking or pushing over the ann unciator-shutter, said armature beingheld to the core until the shutter has been returned by hand to itsnormal position; sixth, to provide a row of spring-jack switches on onecommon receiving wire or circuit, so that when any right-handswitch-plug is connected with any line spring-jack switch it willconnect said line with the operators receiving-telephone.

We will now particularly describe our central-office switchboard systemand the method of operating it by reference to the accompanyingdrawings, in which- Figure 1 represents a front diagrammatic viewillustrating our transfer-board and showing a series of line -wires,double binding posts or washers arranged in three sections, the ground1i ghtnin g-arrester post, having the insulated wires of slightresistance coiled around them, said posts being riveted to aground-plate which is connected with the earth and the interchangeabletransfer-wires of two adjacent sections. Fig. 2 represents a verticalsection of transfer-board, showing the electrical circuits connecting itwith the line and the switchboard. Fig. 3 represents a vertical sectionof the switchboard, show ing our spring-jack switches and the polarizedannunciators in side elevation. Fig. at represents a front View of oneof the annunciators with the elbow-shutter closed. Fig. o'represents asideele-vation, with parts in section, of the right and left handswitch-pin gs. Fig. 6 represents a side elevation of the shoulderrestreceiver in connection with the inductioncoi'l, switchboard,transmitter, and battery. Fig. 7 represents a side elevation of thenightbell annunciator and the connections with the switchboard andground. Fig. 8 represents a front view of the ground-lug. Fig. 9represents an enlarged sectional View of apart of the switch-plu g,showing our clinch or too coupling device. Fig. 10 represents anenlarged vertical sectional view of the front end of the spring-jack,showing the insulation and ringing-spring. Fig. 10 represents ahorizontal section of the view shown in Fig. 10.

Our transfer-board, as represented in Figs. 1 and 2, consists of a boardor other insulating material about twelve inches wide by twenty incheslong and provided with three sections, as A, B, and C, of double endbinding-washers a, b, and c, placed vertically, as shown; also, aground-plate D, secured to the board between the sections A and B andprovided with lightning-arrester posts cZ, having coiled upon them theinsulated wires (1 of slight resistance. The ground-plate D consists ofcopper or other good conducting material about one-quarter of an inch inthickness and one inch or more wide, according to the necessities of thecase, and has riveted or otherwise secured to it the perpendicularground lightningarrester posts (1, about onehalf an inch long. Plate Dis connected with the ground by wire d. Binding-posts a a are applied atthe opposite ends of the elongated washers a, and similar binding-postsb b and c c" are applied, respectively, at the opposite ends of theelongated washers b and 0.

By means of the elongated washers a and b, with their double rows ofbinding-posts in sections A and B, any of the insulated wires d" may beromoved or adjusted without disturbing the trunk-line wires 0*. By meansalso of the elongated washers b and c, with their double rows ofbinding-posts in sections B and C, any of the transfer-wires connectingthe bindingposts b of section B with the binding-posts c of section (Jcan be removed or rearranged without disturbing the switch board-wires cor any other parts of the transfer-board. This arrangement is quiteadvantageous in practice.

In Fig. 2 the line-wire r is shown connecting thebinding-post a with thedistant telephone R and the switchboard-wire 0' connecting thebinding-post c" with the switchboard P, which is shown on agreat1y-reduced scale.

Our transfer-board possesses the advantage of being very compact inconstruction and arrangement and of being provided with groundlightning-arrester posts, each having coiled upon it an insulated wireconnecting with the trunk-lines and the posts being normally connectedwith the earth, making it certain that if an extra heavy atmospheric orother high-tension current flows in over the trunk-line it will burn theinsulation off from the resistance vire, thereby conducting the currentdown through the post and thence to the earth instead of to theswitchboard.

The annunciators J J and the spring-jack switches P, Q, and V aremounted horizontally in the switchboard P, as shown in Fig. 3.

The spring-jack switches P and Q consist each of a frame or line-wireshoe E, having in its upper face at the front end a groove a, Fig. 10,end face-plate c, and a downwardly-extending opening 9, containinginsulating material f, having an opening for the upwardly-bent end ofthe ringing-spring f, as shown in Figs. 10 and 10". The shoe E is setinto an opening q in the switchboard -P and is secured in place byscrews passing through the front end plate e. The ringingspring f isplaced in an openingin the switchboard and is secured by a screw at theback thereof, as shown in Figs. 3 and 10, and is connected by wire in acircuit to be hereinafter described. To the rear end E of the shoe E issecured the flat annunciator-spring e through the medium of the plug gof i11- sulating material and by means of insulated binding-screws e".The rear end of spring 6 is turned upward and provided with abinding-post g, and the front end is bent at a w to form a bow g for thepurpose of engaging with an arm 6 of the ground-lug e, and also forpermitting the passage of switch-plugs below said ground-lug, as will behereinafter described. The ground-lug e is secured to the back of theswitchboard P, and its arm 6 passes transversely below the bow g of theannunciator-spring 6. By arranging the arm 6" of the ground-lug withinthe bow g the switch-plug may be passed into the switchjack in contactwith spring 6 without making connection with the said lug.

Right and left hand sWitch-plu gs G and II are used for makingelectrical connection, and they are preferably provided with benthandles K, of insulating material, and are connected by the conductor K,covered with insulatingmaterial. The plug Gis constructed with fiatstrips of metal G and G, secured to the under side of strip h ofinsulating material. The metal strip G connects with the metallic partof the handle, which is in circuit with the conductor K. Metallic stripsG G are separated at their adjacent ends by a narrow strip of insulatingmaterial 72, A downwardly-extending lug h is secured adjacent to thehandle for indicating to the operator the lower side of the plug, sothat he may never make the mistake of inserting it in the switch-jackupside down.

Each of the plugs is constructed with a de tachable metallic section I,having screwthreaded ends, and a longitudinal passage 1', as shown inFig. 9, and the adjacent portions of the handle are formed withscrew-threaded sockets for receiving said section I. Into the inner endof the longitudinal passaget' is inserted the headed binding-pin i, thehead of which is provided with a transverse slot for receiving theconducting-wire K, which is coiled around the stem of the plug, asshown. This metallic section I and detachable pin 6 form a convenientand reliable electrical connection or coupling.

The right-hand switch-plug II is similar in appearance to the left-handplug G, but has a continuous metal strip G at the upper side and a stripof insulating material 7t at the IOU under side. It also has thedownwardly-extending lug h, of insulating material, as above described.

In the receiving spring-jack V no groundlug c is used, and theelectrical connections are different from those in the spring-jacks Pand Q, as will be hereinafter set forth in the description of theoperation.

The annunciators J J are set horizontally in openings Z in theswitchboard P and consist of the electromagnetic coils L and L, thepolarized field-magnets L, the swinging armature L, the latter. beingpivoted at N to the magnet L and having pivotally connected to its lowerend the push-needle 0, which eX- tends forward through the front plateM, so as to bear at its front end upon the shutter M. The pivotal pin Nis of some diamagnetic material, and thin washers of diamagneticmaterial should be placed between the joints to preventany sticking orretardation of the action of the swinging armature. Instead of usingwashers the end of the field-magnet L may be copper-plated. Theelectromagnetic core at of the magnet is secured at its front end to thefront plate M", which is screwed or otherwise secured to the switchboardP. Plate M is provided at its lower end with an outwardly-projectinghinge-post M and is beveled at its lateral inner edges, so as to receivethe number-plate 5. The shutter M is provided with an elbow m, havingdownwardly-turned cars m, which are pivotally connected by a pin m tothe post M.

When the current is sufficiently strong to reinforce the magneticattraction of the polarized electromagnet L or L, the swinging armatureL will be drawn up against the core 11, thereby driving the push-needle0 forward against the elbow m of shutter M and pushing the latter outpast its center of gravity, causing it to fall down against theprojecting hinge-post M, which acts as a stop. There is no chance forshutter M to stick or fail to fall, because when push-needle 0 has beenforced forward by armature L the shutter has been so moved out of placethat it must drop and the armature L will stick to the core n and remainin this position until some force is used to lift the shutter and forcethe push-needle 0 backward, thereby forcing the armature L out ofcontact with core a.

In the night-bell annunciator, Fig. 7, the shutter M is provided at itslower end with a projecting spring 1, which when the shutter falls makescontact with the pin 2. To the front plate M and the pin 2 are connectedthe wires 1) and p, which connect, respectively, to a battery and bell.(Not here shown.) The annunciator-coil L connects by wires 3 and 4 withthe conductors 00 and x", and a switch Y, pivoted at 00, may be shiftedto either of the contacts 00 and 0c.

The receiving spring-jack V connects by wire 25 to the spring V, securedto the under side of the board Q, which spring is normally in contactwith the contactpiece t, which connects by wire 25 with theinduction-coil 8, which in turn connects by wire t with the receiver9,-which connects by wire to with the earth 12. The operatorstransmitter 6 0011- nects by wire through battery 7 with theinduction-coil 8 and also directly with said coil. The receiver 9 isconstructed with a compound curved magnet 10 and with shoulder-braces wand to, having strips 10 and 11 to hold it firmly on'the shoulder, sothat when the operator pushes the receiver with its earpiece against hisear the said receiver will be se cnrelyheld.BypushingtheplugGashortdistance into the spring-jack P below theannunciator-spring the metallic end strip G makes connection between theinsulated ringingspring f and the shoe E, causing the current to passfrom the alternating magneto-generator to the ringing-spring f throughthe medium of said strip G to the line-wire sh'oe E, thence out on theline 1' to a distant signalbell, thereby avoiding the use of separatepush-buttons or other devices for signaling distant instruments. sinceit has an. insulating-strip h at its under side will not make electricalconnection with ringing-spring f unless it should be inserted upsidedown. The switch-plug G when forced into the spring-jack switch cuts outthe annunciator by lifting the annunciator-spring 6 off from the arm cof the ground-lug e.

The switch-plug H is the annunciator cutin plug. When it is forcedbetween the annunciator-spring e and the shoe E, it leaves the metalstrip G at the upper side of the plug in contact with the spring 6 andforces the current from the outer end E of the shoe, where the line-wireis attached, up through wire r" to the annunciatorL and back throughwire 0 to the annunciator-spring e at binding-post g, and thence out tothe metallic contact-strip G of switch-plug H, thencethrough theinsulating conducting-wire K to the plug G, through its metallic stripG.

Supposing that a message or signal is sent from a distant telephone R tothe central office, the current may be traced as follows: It will flowover line-wire r to the end E of line-shoe E of spring-jack P, thenceover wire 1" to annunciator-coil L, where it will reinforce theelectromagnet L and cause its swinging armature L, carrying thepushneedle 0, to kick or push over the shutter M, and the current thenflows from the coil, through wire r, to the annunciator-spring e atbinding-post g, thence to the ground-lug e and by wire 1) and wire T tothe ground 14. The current may pass either directly by theswitch-contacts Y and m or through the electromagnet L of the night-bellannunciator J 2 and thence through the switch-contacts x and y,depending upon whether switch Y is upon the contact 00 or so. If thecurrent passes through the night-bell annunciator J the operator isnotified that the telephone R The switch-plug H desires a communication.The operator then inserts plug G into spring-jack P, thereby cutting outthe annunciator-coil L.

The operator ascertains that telephone R wishes to communicate withtelephone S. lle then removes plug G from spring-jack I and inserts itinto spring-jack Q, and in doing so first holds the metallic ringing-tipG for a moment between the annunciator-spring e and the ringing-springf, and making electrical connection between said ringin g-sprin g andshoe E, thereby signaling telephone S. The operator then forces plug Gclear into the spring-jack Q, causing spring a to rest in contact withthe insulating material it of the plug and raising said spring up fromcontact with the arm 6 of the ground-lug 6, thus breaking connectionwith the ground and cutting the annunciator L" out of circuit. He nowremoves the plug H from receiving spring-jack V and inserts it into thecalling spring-jack P, thereby cutting the annunciator-call L intocircuit between the telephone-stations R and S. The complete circuitbetween telephones R and S may now be traced by commencing at station Ras follows: The current passes by line-wire r to the heel E of shoe E ofspring-jack P, thence over wire 'r to annunciator-coil L, thence throughsaid coil back over wire 4'' to annunciator cut-out spring e, connectingwith the metal strip G of switch-plug H, and the current thence flowsout through plug H and the conductor K to the metal strip G ofswitchplug G, which is now in contact with shoe E of spring-jack Q, sothat the current flows out on line-wire u to the telephone-station S.The plug H made no electrical connection with the shoe E, since theinsulating material h on the under side of said plug was in contact withsaid shoe.

The flexible insulated wire K between the two plugs is held in positionby a weight. The ringing-spring f is connected by wire 1; to the powermagneto -generator N. By means of the switch T, contacts T" and T, andthe push-button a connection may be made from the spring-jack V to thepowergenerator N, and calling-signals can then be sent through thereceiving spring-jack V and the switch-plugs to the line. This means andmethod of signaling are preferable to the use of a handmagneto-generator. In case the power magneto-generator N breaks down theswitch T may be moved to contact T, and signals may then be sent to theline bymeans of the hand-generator J Having described our invention,what we claim, and desire to secure by Letters Patent, is

1. The combination with the switchboard, of a spring-jack switch,constructed with an elongated frame composed of a line-wire shoe havinga front socket face-plate and of an annunciator-spring bowed upward oroutward near its front end, and secured at its rear end to the rear endof said shoe, the parts being separated by insulating material, a groundlug, as e, secured to the switchboard above said shoe and having an arma", passing under the bowed portion of said spring and serving tosupport it, and a switch-plug, whereby the plug may be inserted in theswitch-jack in contact with the spring without making contact with saidground-lu 2. In the switchboard a spring-jack switch consisting of aline-wire shoe, having an insulated opening and a front socket-plate,and of an annunciator-spring secured at its rear end to the rear end ofsaid shoe, the parts being separated by insulating material, incombination with a ground-lug, supporting said spring near its frontend, a ringing-spring projecting up through said insulated opening inthe shoe, and a switch-plug having a metallic tip for making contactwith said spring, substantially as described.

3. In a switchboard, a spring-jack switch, constructed of an elongatedframe or shoe, having an insulated opening, and of an insulatedannunciator-spring, in combination with a ringing-spring projectingthrough said insulated opening in the shoe, and a switchplug havinginsulating material on one side and a metallic contact-tip at its otherside for making contact with said ringing-spring, substantially asdescribed.

4. The combination with the switchboard, of an annunciator having afront plate, provided at its lower end with a projecting horizontalhinge-post as M, a drop-shutter, having an outwardly-inclined kneeprojection m, at its lower edge and provided with inwardlyprojectingears m, pivotally connected to said post M; also having a field-magnet,a polarized pendulous armature pivoted thereto, a push-needle pivotallyconnected to and operated by said armature and hearing at its oppositeend against said drop-shutter for pushing it over, substantially asdescribed.

5. The combination with the switchboard of the spring-jack switches, apolarized annunciator, companion switch-plugs, one plug being insulatedon the upper surface and the other on the under surface and applied, onefor the purpose of cutting out the annunciator and the other for thepurpose of bringing the annunciator into circuit, substantially asdescribed.

6. In a switchboard, the combination with a spring-jack switch having anannunciator in circuit of a pair of switch-plugs, one plug insulated onthe under surface and the other plug insulated on its upper surface andhaving at the outer end a ringing-tip, insulated from the plug proper,substantially as shown and described. 7

7. In combination with a switchboard, polarized annunciators, springjackswitches, and companion switch-plugs, one plug being insulated on theupper surface and the other on the under surface for cutting oneannunciator into circuit and the other annunciator out of circuit,substantially as described.

8. In combination with a switchboard a polarized needle-push annunciatora springjack switch, having an insulated ringing spring or contact and aswitch-plug having insulating material on one side and a metalliccontact tip or lug at its other side and outer end for the purpose ofbringing the rin gin g-sprin g into circuit with a distant bell,substantially as described.

9. A spring-jack switch having a line-shoe and an annunciator-springsecured to said shoe, in combination with a ground-lug secured to saidswitchboard, said spring resting at one end on said lug, a needle-pushannunciator wires connecting said shoe with the annunciator, andswitch-plugs connected by a conductor, one of which, when inserted intothe spring-jack lifts the annunciator-spring from contact with saidground-lug, cutting off all connection with the ground-wires exceptthrough said plugs,substantially as described.

10. In a switchboard, the combination with the spring-jack switcheshaving line-shoes, of the switch-plugs in pairs, having one side ofmetal and the other of insulating material, the metal part of one beingon the top and the metal part of the other being on the bottom, and alsohaving downwardly-projecting lugs of insulating material and said pairsof plugs sage, z', in combination with a binding-pin, t",

having a slotted head and a stem inserted in said passage 1 forconnecting a conductingwire, substantially as described.

13. In a switchboard a spring-jack switch, having an elongated frame orshoe, provided near its front end with an insulated opening, incombination with a ringing-spring, projecting through said opening, anda switchplug having a metallic tip at its front end for making contactwith said spring for sending signals over the line-wire, substantially-as described.

In testimony whereof we aftix our signatures in presence of twowitnesses.

WILLIAM S. HARRISON. E. M. HARRISON.

Witnesses:

ELIZABETH ENGSTROM, J. E. HoL-YoKE.

